Did da Vinci Create a 3D 'Mona Lisa'?

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Leonardo Da Vinci's "Mona Lisa" painting may be part of the
oldest 3D artwork, say two visual scientists.

In 2012, scientists discovered that beneath layers of black
paint, a seemingly insignificant "knock-off" of
the "Mona Lisa " in the Museo del Prado in Madrid was in
actuality very close to the original hanging in the Louvre
Museum in Paris, revealing the same subject with the same
mountain landscape background. That painting may have been
painted by Da Vinci or possibly one of his students.

"When I first perceived the two paintings side by side, it was
very obvious for me that there is a very small but evident
difference in perspectives," study researcher Claus-Christian
Carbon of the University of Bamberg in Germany wrote in an email
to Live Science. "Maybe the view of a perceptual psychologist is
highly sensitive for such tiny differences, but it is very clear
that also persons who are not so strongly involved in perceptual
sciences can see it easily after having received information on
the change in perspective." [ See
Images of "Mona Lisa" Paintings in 3D ]

Turns out, the real "Mona Lisa," or "La Gioconda," and
the Prado cousin were painted from slightly different
perspectives. Carbon and Vera Hesslinger of Germany's University
of Mainz figured out this perspective shift by looking at
so-called trajectories, or the paths from a distinctive point on
the source, such as the tip of Mona Lisa's nose, to a target, or
the observer's (or painter's) eyes. The scientists also asked
people to estimate the perspective of the "Mona Lisa" sitter,
something Carbon called a psychological assessment of the
perspective.

"This is particularly clear if you observe the chair on which La
Gioconda sits: In the Prado version, you can still see the end of
the end corner of the chair at the background of the painting,
which you cannot see in the Louvre version, because the painter
of the Prado version looked at the' Mona Lisa' more from the left
than the painter of the Louvre version," Carbon said.

The researchers then could recalculate the position the painters
took relative to each other and to
the "Mona Lisa" sitter in Da Vinci's studio. They found that
the horizontal difference between the two paintings was about 2.7
inches (69 millimeters), which is close to the average distance
between a person's two eyes. (When a person observes an object,
each eye sees a slightly different perspective of the object,
both of which are sent to the brain and transformed into the
three-dimensional representation of the object that we "see.")

From these results, the pair thinks the two paintings form a
stereoscopic pair, meaning when viewed together create an
impression of depth,
a 3D image of the "Mona Lisa."

The finding "is accurate in its analysis of the images and
interpretation of a possible intent at a stereoscopic
representation of the hands area," Martin Arguin, of the
University of Montreal, wrote in an email to Live Science, after
looking through Carbon and Hesslinger's journal articles on the
subject.

Did Leonardo
Da Vinci, and possibly one of his students, intentionally
create this stereoscopic pair?

The researchers, of course, can't be sure one way or the other,
but Carbon points out that Da Vinci "intensively worked on the 3D
issue." In addition, in inventory lists there were hints of the
existence of two "Mona Lisa" paintings on his property at the
same time, and that he owned colored spectacles, Carbon said.
[ Leonardo
Da Vinci's 10 Best Ideas ]

This evidence "might indicate that he did not only [think] about
the 3D issue theoretically but in a very practical sense in terms
of experiments," Carbon added. Also, when looking at the original
colors of the two paintings the only real difference was in the
sleeves, in which they are reddish in one version and greenish in
the other. "This could be a hint to Leonardo’s approach to look
at the two La Giocondas through red-green (red-cyan) spectacles,"
he said, similar to those one might don to watch a 3D movie.

"Still, despite all these indications, we have not found final
proof for our hypothesis," he said.

Others suggest the evidence isn't there for an intentional
creation of a stereoscopic view for paintings.

For instance, the disparities between the two paintings for other
areas of the body, not the hands, don't fit with them creating a
stereoscopic pair, according to Arguin. "Most in contradiction
with this notion is the fact that these disparities are largely
oriented vertically, and not horizontally as would be required to
replicate the left and right eye views," Arguin said.

He gave an example of
Mona Lisa's face : "All the landmark location changes are of
the same size. This would not be so in an adequate stereoscopic
image since disparities should vary according to relief (i.e.
distance from the observer)."

Arguin added of the study: "They are quite accurate in their
statements, and their discussion of their findings is sensible
and interesting."

Carbon and Hesslinger say they agree with Arguin's comments about
the consistency of disparities in certain regions of
the "Mona Lisa" paintings and the horizontal or vertical
nature of some of the disparities between the two paintings.

"Ideally we need horizontal disparities to create a proper 3D
impression, which we mainly revealed for the hands region,"
Carbon told Live Science. "This is also the reason for having
focused on the hands region when reconstructing the 3D image and
visualizing the 3D effect."

Carbon added: "As conclusion we would like to qualify the
stereoscopic properties of this region 'remarkable' and
'intriguing,' particularly when we take into account that the
base pictures stem from the very early years of the 16th
century."

Editor's Note: This article was updated to
add responses from Carbon and Hesslinger to Arguin's
comments.